Traffic Management for the Available Bit Rate (ABR) Service in ...

2. It must have a value less than 1 when the queueing delay, Tq is greater than
T 0. This forces the queues to decrease and Tq can go down to T 0. Since queue
increases are due to tra c bursts, a more aggressive control policy is required
for this case compared to the former case where we project a higher capacity
than available. Since we project a lower capacity than what is available, the
remaining capacity is used to drain the queues.
3. If the queues grow unboundedly, then we would like thefunction to go to zero.
Since zero, or very low, ABR capacity is unacceptable, we place a cuto on
the capacity allocated to queue drain. The cuto is characterized by a param-
eter, called the queue drain limit factor (QDLF). A value of 0.5 for the QDLF
parameter is su cient in practice.
4. When the queueing delay, Tq is T 0we want f (Tq) =1.
Figure 6.3: Step functions for ERICA+
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